Safety cut-out for electric circuits.



J. SACHS.

SAFETY CUT-OUT FOR ELECTRiC CIRCUITS.

(Applicntion med Sept. 28, 1899.)

(No Model.)

Patented Nov. 27, I900.

I E O l l o UNITED STATES PATENT EEIcE.

JOSEPH SACHS, OF HARTFORD, CONNECTICUT.

SAFETY CUT-OUT FOR ELECTRIC ClRCUlTS.

SFECIFTGATION forming part of Letters Patent No. 662,501, dated November27, 1900.

Application filed September 28, 1899. Serial No. 781,897. \No model.)

To all whom it may concern:

Be it known that l, JOSEPH SACHS, a citizen of the United States,residing at Hartford, in the county of Hartford and State ofConnectiout, have invented an Improvement in Safety Cut-Outs forElectric Circuits, of which the following is a specification.

My invention relates to a fuse device adapted to operate with thesmallest and most delicate electric currents. I-Ieretofore it has beendifficult if not quite impossible to produce fuses sensitive toexceedingly-small electric currentssuch, for instance, as are employedfor telephones, telegraph instruments, firealarms,and similar apparatus.My improved safety-fuse or cut-out is adapted for use generally, butparticularly with instru ments and in places where the smallest electriccurrents are employed, the fuse being adapted to open the circuit atvery small overload electric currents, and the arrangement isexceedingly simple, cheap, and efficient.

In carrying out my present invention 1 provide a section orpiece ofhigh-resistance heating material-such as graphite, or carbon, ormetal-and to this is connected a portion or Wire which is ofcomparatively low resistance or melting-point. These parts are in oneline and preferably provided with suitable terminals and within a caseof suitable insulating material. In this case the wires may be suspendedbetween the terminal ends and the case may be tubular, and it may bewholly or partially filled with some suitable material, such as thematerial heretofore shown and described by me in former applications.The portions or wires extending from the opposite ends of the section ofhigh-resistance material may be entirely straight or partially or whollycoiled. Where the wires are coiled, they are preferably short lengths,either connecting the circuit connections or metal terminals with theends of the Wires that are connected to the high-resistance material orextending between the high-resistance material and one circuitconnection, and the special object of the coils is to normally produce atension upon the intermediate parts, so as to maintain them in asuspended condition without perceptible sagging and to pull the partsasunder when fused under an excess current. The metal terminals orcircuit connections may be either notched plates or the metal ends orcaps of the inclosing case of insulating material. The case or inclosurefor the wires may be tubular and of insulating material or a fiat stripof insulating material with an open center. The ends of the wires may beconnected to the piece of high-resist ance material in any desiredmanner well known in the arts, particularly those hereinafter set forth.

In the drawings, Figure 1 is an elevation of the fuse device alone.Figs. 2 and 3 are elevations of modified forms of the fuse device alone.Fig. i represents the fuse device in an inclosing' tubular case. Fig. 5represents the fuse device in an insulating holder having an opencenter, and Fig. U represents a modification of the fuse device alone.

The wire or wires a are of some comparatively low melting or resistancemetal,through which the current is conductedsuch, for instance, as lead,tin, zinc, copper, or suitable alloys of the same. The short section ofhighresistance heating materialb such as graphite, carbon, or similarmaterial or a com pound or metal whose melting-point is very much higherthan that of the wire ahas one of the ends of the wire connected to it.This connection may be by twisting the ends of the wire a around thesection b or by clamping it thereto or by soldering the end of the wirea to the end of the section b.

in Fig. 1 one end of the section b is con nected directly to oneterminal and the other end to a wire a, while in Fig. 2 the respectiveends of the section bare connected to the wires a, which in turn areconnected to the terminals or circuit connections. Vifhere the section bis of graphite or carbon and the ends of the wires a are solderedthereto, it is preferable that the section b be first electroplated. Thesoldering material may be of any suitable character well known in thearls, and in cases where the wires a co are of lead they may beconnected to the section b without solder, their ends being simplymelted to a connection with the section b, or, in other words, joineddirectly when the proper degree of heat is applied.

The terminals or circuit connections 0 may be notched plates, as shownin Figs. 1, 2, 3, and 6, or end caps d, as shown in Fig. -l-, or

plain plates 6, as shown in Fig. 5. The ends of the wires a a may beconnected directly to the circuit connections or terminals 0, as shownin Fig. 2, or one of them may be connected directly, as shown in Fig. 6,or I may employ coilsff between the ends of the wires d and theterminals or circuit connections, as shown in Figs. 3, 4, and 5, or Imay employ only one coil, as shown in Fig. (5, and extend the samebetween the section b and the terminal c. The special object of thecoils f, which, by the way, are preferably made of metal having a degreeof spring thereto, is to normally apply a tension to the wires to andsection 1) between the terminals, so as to hold the same in anapproximately straight line.

In Fig. 4 I have shown a surrounding case 9, of insulating material andof tubular form, with circuit connections or terminals (1 in the form ofend caps of metal fitting over the open ends of the tubular case, withthe ends of the coils connected directly to the end caps and the wires aand section I) under tension and centrally of the said case J.

In Fig. 5 I have shown a case or holder 7A, of a flat strip ofinsulating material, with an open center and with plate-terminals e inthe respective ends of the holder h and in which the coilsf maintain thewires CL and section I) under tension and centrally of the holder h.

The tubular case g, of insulating material, may be glass, rubber, fiber,asbestos, or similar suitable substance and the metal caps at the endsserve as the terminals themselves, and they may be connected to anysuitable foundation similar to what has heretofore been shown in myother applications and patents. The interior of this tubular case 5 maybe unfilled or may be filled by any suitable material or it may bedivided and partially filled, as has heretofore been customary with mein similar devices.

In the operation of this device the current passes from one end to theother between the terminals or circuit connections and over the wires aand the section b, and the parts are so proportioned that the wires toCb are scarcely heated at all by the passing of the electric current,but the section b is considerably heated. This is due to the fact thatthe section 1) consists of a concentrated resistance, and while it maynot be of any great length yet the heat generated by the section b wherethe parts are properly proportioned will even with the smallest overloadelectric current be enough to melt the'connection between a wire a andthe section Z) either in severing the wire connection or in melting thesolder, so that there is a separation of the parts which breaks theelectric circuit. In cases where the coiled terminal wires are used thisdisj ointing is really assisted bythe tension kept upon the fuse-wire,so that as soon as suflicient heat is produced from the overload-currentthe parts will be pulled asunder. I prefer to employ a tubular case, asshown in Fig. 4, be cause the same is the most satisfactory and the bestadapted for the purposes, as thereby the same protects the fuse devicefrom all aircurrents and contact with other bodies, and therein the fusedevice is supported in a medium the condition and character of which arenot readily changed or affected by outside conditions.

I do not limit myself to the supporting device for the safety cut-out orto the manner of connecting the ends of the wires or coils to the pieceZ) of high resistance or to the form of the circuit connections orterminals.

I claim as my invention 1. A safety-fuse comprising two connectedportions in one line for the passage of the electric current, the oneportion. a section of material of low conductivity to be heated and theother portion a piece of material of high conductivity connected by ajoint fusible by an excess of heat of the low-senductivity section,substantially as specified.

2. The combination in a safety-fuse with circuit connections and thefusc-wirc connected thereto, of a section of graphite, carbon or similarhigh-resistance heating material to which the fuse-wire connected by ajoint fusible by the action of excess of heat of the heating-sectionsubstantially as spccilied.

3. A safety-fuse comprising two connected portions in one line for thepr of the electric current, the one portioi material of low conductivityto l' heated and the other portion a piece of material of highconductivity connected by a join t .iible by an. excess of heat of thelow-cowluctivity section, and a means for effecting nsion for theseparation of the parts, substantially as specified.

-l-. A safetyfnsc comprising two connected portions in one line for thepassage of the electric current, the one portion a section of materialof low conductivity to be heated and the other portion a piece ofmaterial of high conductivity connected by a joint fusible by an excessof heat of the low-conductivity section and a tubular case holding thesaid parts, and terminals to which the endsthereof are connected,substantially as specified.

5. The combination in an electric safetyfuse with a higlrresistaneeheating-section, of a coiled wire connected electrically andmechanically by a fusible joint to and in one line with thehigh-resistance section and by which a tension is normally effected onthe parts and a separation when the resistancesection has been heated toexcess and the fusible joint melted, substantially as and for thepurposes set forth. I

G. The combination in a safety-fuse, with circuit connections and thefnse-vires, of a short section of graphite, carbon or similarhigh-resistance material interposed between the fuse-wires and to whichthe ends of the same are connected by a joint fusible by an excess ofheat of the higlrresistance material, substantially as specified.

7. The combination in a safety-fuse with circuit connections and thefuse-Wires connected thereto, of a short intermediate section ofgraphite, carbon or similar high-resistance material electroplated andto which the respective ends of the fuse-Wires are soldered,substantially as set forth.

8. The combination in a safety-fuse with the fuse-Wires, of aninterposed section of high-resistance material to which the fuse- Wiresare connected, circuit connections and coils connecting the respectivecircuit connections and the free ends of the fuse-Wires, substantiallyas set forth. 7

9. The combination in a safety-fuse with a tubular case of insulatingmaterial and metal circuit connections or terminals at the re spectiveends thereof,of fuse-Wires connected to the said terminals Within thecase and an interposed section of high-resistance material connected tothe fuse-Wires Within the case by a joint fusible by an excess of heatof the high-resistance material, substantially as set forth.

10. The combination in a safety-fuse witha tubular case of insulatingmaterial and metal end caps forming circuit connections orterminals, ofthe fuse-Wires, an interposed section of high-resistance materialconnected to the fuse-Wires and coils connecting the ends of thefuse-Wires to the end terminal caps, sub stantially as set forth.

11. The combination in a safety-fuse with a holder of insulatingmaterial and metal circuit connections or terminals at the respectiveends thereof, of fuse-wires connected to the said terminals and aninterposed section of high-resistance material connected to thefuse-Wires by a joint fusible by an excess of heat of thehigh-resistance material, substantially as set forth.

Signed by me this 21st day of September, 1890.

JOSEPH SACHS.

Witnesses:

Gno. T. PINCKNEY, S. T. HAVILAND.

